Here’s a great chart from a
terrific 2008 manuscript that gives a hint of our complex ecosystem. I think we’ll look back on this time with some nostalgia– much as we did in the pre-antibiotic era or perhaps the pre-bloodletting era. As our tools move from Pasteur to CSI, so does our understanding of the microbiome.
Adapted from Glausiusz, Discover Magazine, June 2007, as well as images courtesy of the National Institutes of Health, National Cancer Institute, Centers for Disease Control, and Wikipedia. This figure depicts different microbes and other organisms that have been intimately associated with humans as commensals or potential pathogens. The numbers correspond to images of organisms and approximate anatomic locations where these organisms may reside on the human body. 1. Trichophyton and Epidermophyton are filamentous, parasitic microbes that cause athlete’s foot. 2. Vaginal microbiota, mostly Lactobacillus species secrete lactic acid and other antimicrobial compounds that prevent pathogen overgrowth. 3. More than 500 species of bacteria, weighing approximately 3.3 pounds in the average human adult, live inside the gastrointestinal tract. 4. More than 100 strains of human papillomavirus (HPV) can infect humans, causing a variety of warts from the common wart to plantar and flat warts. 5. Pediculus humanus capitis, the head louse, may have co-evolved with recent H. sapiens. 6. Oral Streptococcus species form biofilms that may be 300–500 cells in thickness on the surfaces of unbrushed teeth. 7. Demodex mites inhabit the follicles of the eyelashes and infest about 20 percent of people under the age of 20. 8. After initial infection with the varicella-zoster virus (chickenpox), the virus remains dormant in nerve ganglia and may cause disease due to re-activation later in life. 9. Approximately 1/12 of the human genome consists of DNA from fossil viruses that infected human ancestors millions of years ago. 10. Prevalent bacterial genera on the human skin include Streptococcus, Staphylococcus, and Corynebacterium.